Optical and Magnetic Instruments for Mapping the Ocean Floor

Ocean-floor mapping requires good geodetic control and the use of sensors capable of detecting features on and below the water-bottom interface. Optical sensors have been useful. Film cameras with their permanent record are preferable to human observers and television. Since the loss of the Thresher the effectiveness of cameras has been increased by the use of wide-angle lenses and larger film loads. Recent experiments indicate that further gains will result from locating the lights behind the camera. Magnetic sensors are useful adjuncts to deep sea cameras. In many cases the causes of magnetic anomalies are visible in photographs made at the same time.